According to the World Steel Association, there are over 3,500 different grades of steel, encompassing unique physical, chemical, and environmental properties. In essence, steel is composed of iron and carbon, although it is the amount of carbon, as well as the level of impurities and additional.2017-7-1

Steel is an alloy of iron and carbon and other elements. Because of its high tensile strength and low cost, it is a major component used in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons.. Iron is the base metal of steel. Iron is able to take on two crystalline forms (allotropic forms), body centered cubic 2018-4-6

Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties.Alloy steels are broken down arbitrarily: [clarification needed] Smith and Hashemi define the difference at 4.0%, while Degarmo, et al., define it at 8.0%. Most commonly, the phrase "alloy steel" refers to low-alloy 2018-4-3